This is the upgraded version of it’s predecessor RTCMV2.1. It is optimized for reference station networks. outside of the two usual combinations 18/19 (raw phase and code data) or 20/21 (corrections to phase and code data), now there is also RTCM type 23 that is being send. Type 23 contains information that is about the refence station’s antenna. With RTCM type 24 you can send accurate reference station coordinates. when the program recognizes type 23, it automatically chooses the right antenna model. This gives you improved altitude positioning, it also provides shortened Initiation times.

RTCMV3.X is the completely revised version of the 2.3 version. It is a little bit more rugged and better to interpret by a GNSS receiver. It also way more compact in comparison to its predecessor (V2.3).
It contains additional messages for the use of an RTK network. This happens according to the Master-Auxiliary Concept (MAC), it also offers extra information about network residues (ionosphere) and coordinate transformations.